Publications by authors named "Alex A Blacutt"

4 Publications

  • Page 1 of 1

Synthesis of Deoxyradicinin, an Inhibitor of and , a Culturable Surrogate for Liberibacter asiaticus.

J Nat Prod 2020 06 8;83(6):1810-1816. Epub 2020 Jun 8.

Department of Chemistry, Point Loma Nazarene University, San Diego, California 92106, United States.

Pierce's disease of grapevine and citrus huanglongbing are caused by the bacterial pathogens and Liberibacter asiaticus (Las), respectively. Both pathogens reside within the plant vascular system, occluding water and nutrient transport, leading to a decrease in productivity and fruit marketability and ultimately death of their hosts. Field observations of apparently healthy plants in disease-affected vineyards and groves led to the hypothesis that natural products from endophytes may inhibit these bacterial pathogens. Previously, we showed that the natural product radicinin from sp. inhibits . Herein we describe a chemical synthesis of deoxyradicinin and establish it as an inhibitor of both and , a culturable surrogate for Las. The key to this three-step route is a zinc-mediated enolate -acylation, which allows for direct introduction of the propenyl side chain without extraneous redox manipulations.
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http://dx.doi.org/10.1021/acs.jnatprod.9b01207DOI Listing
June 2020

Fungal Lactamases: Their Occurrence and Function.

Front Microbiol 2017 19;8:1775. Epub 2017 Sep 19.

Toxicology and Mycotoxin Research Unit, U.S. National Poultry Research Center, United States Department of Agriculture - Agricultural Research Service, AthensGA, United States.

Fungi are absorptive feeders and thus must colonize and ramify through their substrate to survive. In so doing they are in competition, particularly in the soil, with myriad microbes. These microbes use xenobiotic compounds as offensive weapons to compete for nutrition, and fungi must be sufficiently resistant to these xenobiotics. One prominent mechanism of xenobiotic resistance is through production of corresponding degrading enzymes. As typical examples, bacterial β-lactamases are well known for their ability to degrade and consequently confer resistance to β-lactam antibiotics, a serious emerging problem in health care. We have identified many fungal genes that putatively encode proteins exhibiting a high degree of similarity to β-lactamases. However, fungal cell walls are structurally different from the bacterial peptidoglycan target of β-lactams. This raises the question, why do fungi have lactamases and what are their functions? Previously, we identified and characterized one lactamase encoding gene (FVEG_08291) that confers resistance to the benzoxazinoid phytoanticipins produced by maize, wheat, and rye. Since benzoxazinoids are γ-lactams with five-membered rings rather than the four-membered β-lactams, we refer to the predicted enzymes simply as lactamases, rather than β-lactamases. An overview of fungal genomes suggests a strong positive correlation between environmental niche complexity and the number of fungal lactamase encoding genes, with soil-borne fungi showing dramatic amplification of lactamase encoding genes compared to those fungi found in less biologically complex environments. Remarkably, species frequently possess large (>40) numbers of these genes. We hypothesize that many fungal hydrolytic lactamases are responsible for the degradation of plant or microbial xenobiotic lactam compounds. Alignment of protein sequences revealed two conserved patterns resembling bacterial β-lactamases, specifically those possessing PFAM domains PF00753 or PF00144. Structural predictions of lactamases also suggested similar catalytic mechanisms to those of their bacterial counterparts. Overall, we present the first in-depth analysis of lactamases in fungi, and discuss their potential relevance to fitness and resistance to antimicrobials in the environment.
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http://dx.doi.org/10.3389/fmicb.2017.01775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5610705PMC
September 2017

Fusarium verticillioides: Advancements in Understanding the Toxicity, Virulence, and Niche Adaptations of a Model Mycotoxigenic Pathogen of Maize.

Phytopathology 2018 Mar 2;108(3):312-326. Epub 2018 Jan 2.

First and fourth authors: Department of Plant Pathology, University of Georgia, Athens 30602; and second, third, and fifth authors: United States Department of Agriculture-Agricultural Research Service, U.S. National Poultry Research Center, Toxicology and Mycotoxin Research Unit, Athens, GA 30605-2720.

The importance of understanding the biology of the mycotoxigenic fungus Fusarium verticillioides and its various microbial and plant host interactions is critical given its threat to maize, one of the world's most valuable food crops. Disease outbreaks and mycotoxin contamination of grain threaten economic returns and have grave implications for human and animal health and food security. Furthermore, F. verticillioides is a member of a genus of significant phytopathogens and, thus, data regarding its host association, biosynthesis of secondary metabolites, and other metabolic (degradative) capabilities are consequential to both basic and applied research efforts across multiple pathosystems. Notorious among its secondary metabolites are the fumonisin mycotoxins, which cause severe animal diseases and are implicated in human disease. Additionally, studies of these mycotoxins have led to new understandings of F. verticillioides plant pathogenicity and provide tools for research into cellular processes and host-pathogen interaction strategies. This review presents current knowledge regarding several significant lines of F. verticillioides research, including facets of toxin production, virulence, and novel fitness strategies exhibited by this fungus across rhizosphere and plant environments.
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http://dx.doi.org/10.1094/PHYTO-06-17-0203-RVWDOI Listing
March 2018
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